You could make a good Fantastic Four movie. The problem is that the time to make it was years ago. We’ve had three pretty bad ones now, and it’s probably going to be hard to start up and go at this point.
Anyway, Captain America as a superhero identity may end up being passed to Bucky Barnes. It’s not guarranteed, but it is possible. I don’t think Disney wants or need another Iron Man, though. It’s really well associated with RDJ, and that’s enough. Marvel was able to fire up an entire series of movie, and they have huge new opportunities to go forward with. With only a few slots to release in any given year, it’s going to be hard to add another Cap or Iron Man movie to the pile for a long time.